90991991091 has 4 divisors (see below), whose sum is σ = 121322654792. Its totient is φ = 60661327392.

The previous prime is 90991991033. The next prime is 90991991093. The reversal of 90991991091 is 19019919909.

It is a semiprime because it is the product of two primes.

It is a de Polignac number, because none of the positive numbers 2^k-90991991091 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (90991991093) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15165331846 + ... + 15165331851.

It is an arithmetic number, because the mean of its divisors is an integer number (30330663698).

Almost surely, 2^90991991091 is an apocalyptic number.

90991991091 is a deficient number, since it is larger than the sum of its proper divisors (30330663701).

90991991091 is a wasteful number, since it uses less digits than its factorization.

90991991091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30330663700.

The product of its (nonzero) digits is 531441, while the sum is 57.

The spelling of 90991991091 in words is "ninety billion, nine hundred ninety-one million, nine hundred ninety-one thousand, ninety-one".